As the data communication as well as the information technology grows at a high speed, there is an increasingly high demand for the performance of a transmission cable. At present, there exists a composite cable where a signal line and a power line are integrated with each other. For such a composite cable, an effective shield must be provided between power supply transmitted by the power line and signals transmitted by the signal line, interference signals from the outside must be shielded off while signals are being transmitted through the line, and signals transmitted through the line must not interfere with the external environment. In order to meet the above requirements, for some cables, the cable has its core surrounded by a layer of metal net for shield. However, the metal has different shielding capabilities for various physical fields such as an electric field and a magnetic field, so it is difficult for a metal net to meet requirements for shielding different physical fields.